To be or not to be?

What do you do when the family who has graciously offered you their home and use of their kitchen unknowingly attempts to poison you every night?

In London,  I'm staying with a very nice British family who have very kindly taken me and my roommate in, given us our own bedrooms and a bathroom to share, cabinet space and a shelf in their fridge. We're allowed to do our laundry in their washing machine, they have internet that works much better than some of the horror stories of the other students, and the shower is also much better than what we've heard tell. There's good water pressure and so far I have not run out of hot water, nor heard anybody else complain of it. We are provided with breakfast, but have use of the kitchen for lunch and dinner, they only ask that we wash our dishes and wait until they've finished cooking before we start so we don't all try and cram in there at the same time. There is often wonderful smells wafting up the stairs from homemade bread, spaghetti, brownies, and other delicious home cooked meals.

My only complaint is that they live their kitchen messy. Normally this wouldn't be an issue I'd just swipe the crumbs off the table and out of my way, however when bread crumbs give you diarrhea you're a bit more wary of them. There is always a fresh loaf of homemade bread sitting on the kitchen counter and it seems like every other night there is a bowl of covered pasta just hanging out as well. These things aren't necessarily too scary, except for the fact that some of the family cannot seem to grasp the concept of wiping the table, or counter off. And even though they have a dishwasher that they do not use, washing dishes is an issue for them as well. Many times I have pulled a dish out of the cabinet that has leftover grime from last night's dinner. If I can clean my own dishes well enough so that there's no leftover residue and they're actually clean, so can you. I promise it's not rocket science.

How do you tell somebody their house is not clean enough for you when they've invited you in and are allowing you practically free range of their kitchen and the upper two floors of their house? Is there some PC way of telling somebody that they need to learn how to wash dishes?

Do I let it be and clean my dishes before and after I use them, as well as wiping off the table with a possibly dirty sponge before I eat, or do I tell them they suck at cleaning and need to not leave bread crumbs everywhere?